Films of polymeric linear polyesters have excellent draw orientation and have proved especially well suited for biaxial film orientation. These polymeric films, especially those of polyethylene terephthalate or PET, are strong and have excellent inherent chemical and thermal properties. In addition, they have good optical clarity, toughness, and static properties, which makes them extremely suitable for use in photographic and reprographic applications.
In these applications the polymeric film is laminated with a layer of gelatin. However, unprimed polyester film is not very receptive to coating with gelatin. Adhesion between the hydrophobic unprimed polyester film and the hydrophilic gelatin is poor. Although coating that improve the adhesion of gelatin to polyester, such as the vinylidene polymers disclosed in U.S. Pat. No. 2,698,240, there is a continuing need for materials that will improve the adhesion of gelatin to polyester.